Improved expanding tap



UNITED STATES PATENT OFFICE.

G. ADAM OHL, VOF NEWARK, NEW JERSEY.

IMPROVED EXPANDING TAP.

Specification forming part of Letters Patent No. 52,06. dated January 16, 1866.

To all whom it may concern;

Be it known that I, GEORGE ADAM OHL, of Newark, in the county of Essex and State of New Jersey, have invented a new and Improved Expanding Tap; and I do hereby declare that the following is a full, clear, and exact description of the construction and operation ofthe same, reference being had to the annexed drawings, making a part of this specication, in which- Figure 1 is a plan or end view. Fig. 2 is a longitudinal or side elevation. Fig. 3 is a transverse section. Fig. 4: is the expandingnut; Fig. 5, the stock or shank; Fig. G, the

- wrench for expanding-screw; Fig. 7, the expanding-screw, and -Fig. S the cutter or die.

My invention consists in providing means of moving the cutters G up and down in the dovetail slots F at will, thus enlarging or contracting the size of tap, which is often desirable, as when tapping a very thin tube or friable metal, which, with an ordinary tap, would be very liable to break, can be tapped with my improved tap with perfect safety by tapping at first with a light cut on the thread and gradually enlarging or expanding the cutters with each successive tapping until desired size is obtained.

A considerable advantage of my invention is found in the facility with which it can be used in tting bolts ot' varying sizes but the same thread, as are often found in bolts cut in an engine-lathe by an incompetent or careless workman, and which oftentimes, but for my device, would have to be sent to be recut at great expense.

To enable others skilled in the art to make and use my invention, I will proceed to describe its construction and operation.

I drill through the shank S a hole for the reception ot' the expanding-screw E, and counterbore it for the reception ot' the expandingnut N, which is moved longitudinally by means ot' the screw E. I also plane slab or mill dovetail slots F for the reception oi' the cutters C, which slots are at varying distances longitudinally from the axis of the shank, so that it' the cutters C be moved up in these slots F the distance from edge of the cutters C to the axis of shank S is increased, thus enlarging or expanding the tap, and viceversa. rlhese cutters are moved by' means of the screws B pass ing through slots or openings in the shank and engaging the nut N, and thus movedup or down in the slots F as the nutN is drawn up or down by means of the screw E. The nut N is prevented from turning by means of the screws P passing through the shank and into the slot X in the nut- N.

In taps ot' a small size the screw E takes the place ot' the nut N, and the nut is operated at the top, where the collar D is in the annexed drawings.

Another thing (not shown in the drawings) is a scale on shank to indicatethe sizes of tap at different positions ot' cutters. Y

What I claim as my invention, and desire to secure by Letters Patent, is-

1. The peculiar form of shank and the arrangement ot' moving the cutters C by means ot' the internal screw E and nnt N, 0r by any similar device.'

2. The combination of the several parts described in specifications and annexed drawings.

J. ADAM OHL.

Witnesses:

C. C. COLLINS, JOHN E. LYON. 

